Lubricant blends with pao-based dispersants

ABSTRACT

Provided is a lubricant blend including one or more lubricant base stocks and one or more dispersants. The dispersant is chosen from a polyalphaolefin succinimide, a polyalphaolefin succinamide, a polyalphaolefin acid ester, a polyalphaolefin oxazoline, a polyalphaolefin imidazoline, a polyalphaolefin succinamide imidazoline, and combinations thereof. The one or more dispersants are present at 2 to 20 wt % based on the total weight of the blend. The one or more dispersants and the one or more lubricant base stocks are together present at 8 wt % or more of the total weight of the blend. Provided is also a process for making the lubricant blend and a method for the service life of a lubricant.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a non-provisional application that claims priority to U.S.Provisional Patent Application No. 61/474,912 filed on Apr. 13, 2011,herein incorporated by reference in its entirety.

FIELD

The present disclosure relates to lubricant blends includingdispersants. The present disclosure further relates to lubricant blendsexhibiting desirable viscosity properties.

BACKGROUND

Dispersants have been employed in lubricant and fuel formulations toprovide protection against and to stabilize dirt and sludge thataccumulate in the formulations during ordinary use. Dispersantstypically have hydrophilic heads and hydrophobic tails and exhibit theproperties of surfactants. The hydrophilic heads have an affinity fordirt and sludge, while the hydrophobic tails have an affinity for thebase stocks of the lubricant and fuel formulations.

Conventional dispersants most often used in lubricant or fuelformulations have been the type prepared by functionalizingpolyisobutylene (PIB) of varying molecular weights with maleic anhydridefollowed by reaction with polyamines [Lubricant additives, Chemistry andApplications, by L. R. Rudnick, 2003 Marcel Dekker, Inc. New York, NJ10016]. These dispersants work well for conventional lubricant and fuelformulations. In many automotive engine lubricant formulations, 3 to 10wt % of dispersant has typically been used, the highest amount of alladditives used in such formulations.

New lubricants are needed to meet higher automobile fuel economystandards, longer oil drain intervals, and greater operating severity.This need may require the use of even higher levels of dispersantsand/or lower lubricant base stock viscosity. The use of higher levels ofPIB-based dispersants, however, may significantly increase the viscosityof lubricant formulations and render it difficult to attain lower motoroil viscosity grades, e.g., 0W20 and 0W30. Lower viscosity grades formotor oil are particularly important in meeting fuel economy guidelines.

An alternative to increasing dispersant levels is to use lower viscositybase stocks. However, the use of such lower viscosity base stocks canresult in higher volatility (loss of oil) and reduced lubricant oil filmand wear protection on internal engine surfaces.

Thus, there is a need for a dispersant that provides lubricantformulations with effective protection against the effects of dirt andsludge accumulation. There is also a need for a dispersant that provideslubricant formulations with such protection without significant increasein a required amount of dispersant and/or formulation viscosity.

SUMMARY

According to the present disclosure, there is provided a lubricantblend. The blend has one or more lubricant base stocks and a dispersant.The dispersant is selected from the group consisting of apolyalphaolefin succinimide, a polyalphaolefin succinamide, apolyalphaolefin acid ester, a polyalphaolefin oxazoline, apolyalphaolefin imidazoline, a polyalphaolefin succinamide imidazoline,and combinations thereof. The one or more dispersants are present at 2to 20 wt % based on the total weight of the blend. The one or moredispersants and the one or more lubricant base stocks are togetherpresent at 85 wt % or more of the total weight of the blend.

Further according to the present disclosure, there is provided a processfor making a lubricant blend. The process has the step of admixing anamount of the one or more lubricant base stocks and the amount of thedispersant described above in the proportions described above.

Still further according to the present disclosure, there is provided amethod for lengthening the service life of a lubricant. The method hasthe steps of admixing with an amount of the one or more lubricant basestocks and the amount of the dispersant described above in theproportions described above, and utilizing the lubricant formulation asan oil or grease in a device or apparatus requiring lubrication ofmoving and/or interacting mechanical parts, components, or surfaces.

According to the present disclosure, there is provided a lubricant blendprovided by a process. The blend is produced by admixing one or morelubricant base stocks with a dispersant produced by a process ofreacting (A) a polyalphaolefin with a polyamine to yield apolyalphaolefin succinimide and/or a polyalphaolefin succinamide and/orpolyalphaolefin succinamide-imidazoline, or (B) a polyalphaolefin withan alcohol or polyol to yield a succinic acid ester or (C) apolyalphaolefin with an amino alcohol to yield an polyalphaolefinamide-oxazoline. The dispersant is 2 to 20 wt % based on the totalweight of the blend. The dispersant and the one or more lubricant basestocks are together present at 85 wt % or more of the total weight ofthe blend.

DETAILED DESCRIPTION

All numerical values within the detailed description and the claimsherein are modified by “about” or “approximately” the indicated value,and take into account experimental error and variations that would beexpected by a person having ordinary skill in the art.

The polyalphaolefin succinimide (PAO-imide), polyalphaolefin succinamide(PAO-amide), and/or polyalphaolefin succinic acid ester (PAO-ester),polyalphaolefin oxazoline, and polyalphaolefin imidazoline dispersantdisclosed herein provides lubricant formulations with effective andenhanced protection against dirt and sludge such that automobile oildrain intervals can be lengthened and severe operation maintained. Thedispersant provides enhanced protection without need for substantialincrease in amount employed. The dispersant provides enhancedstabilization of dirt and sludge without substantial increase inviscosity, including without substantial increase in kinematic viscosityat 40° C. and 100° C. The dispersant provides improved low temperatureproperties, such as improvement of CCS performance at −15° C. to −40° C.and improvement of low temperature kinematic viscosities at less than−15° C.

The dispersants can be synthesized to have similar amounts of nitrogencontent and similar degree of dispersancy as conventional PIB-imide,PIB-amide and PIB-ester dispersants. The dispersants provide an easierand broader formulation window to reach fuel-efficient viscosity gradesand/or the use of more conventional base stocks of higher viscosity andprovide in better overall performance. PAO also reacts faster withmaleic anhydride than does PIB and affords a greater degree offunctionalization.

Polyalphaolefins (PAO) useful as feedstock in forming the dispersantsare those derived from oligomerization or polymerization of ethylene,propylene, and α-olefins. Suitable α-olefins include 1-butene,1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene,1-undecene, 1-dodecene, 1-tetradecene, and 1-octadecene. Feedstockscontaining a mixture of two or more of the foregoing monomers as well asother hydrocarbons are typically employed when manufacturing PAOscommercially. The PAO may take the form of dimers, trimers, tetramers,polymers, and the like.

The PAO used to prepare PAO-based dispersants may have a M_(W)(weight-average molecular weight) of 450 to 24,000, preferably 600 to20,000, preferably 600 to 18,000, preferably 600 to 16,000, preferably600 to 14,000, preferably 600 to 7,500, and most preferably 600 to4,000. The PAO may have a M_(n) (number-average molecular weight) of 280to 12,000, preferably 400 to 10,000, preferably 500 to 9,000, preferably500 to 7,500, preferably 500 to 6,000, preferably 500 to 4,400,preferably 400 to 1,000, and most preferably 400 to 800. The PAO mayhave a M_(W)/M_(n) or molecular weight distribution of 1.1 to 3.0,preferably 1.2 to 2.5, and most preferably 1.3 to 2.2. The molecularweights of the PAO were measured by a gel permeation chromatographequipped with universal column and calibrated with commercialpolystyrene GPC standard of very narrow molecular weight distribution.The PAO may have a 100° C. kinematic viscosity measured of 2 cSt to1,000 cSt, preferably 3 cSt to 800 cSt, preferably 4 cSt to 600 cSt,preferably 5 cSt to 450 cSt, preferably 5 cSt to 300 cSt, preferably 5cSt to 150 cSt, preferably 4 cSt to 40 cSt, and preferably 4 cSt to 20cSt. The PAO may have a 40° C. kinematic viscosity measured of 4 cSt to12,000 cSt, preferably 10 cSt to 1,000 cSt, preferably 20 cSt to 8,000cSt, preferably 20 cSt to 6,000 cSt, preferably 20 cSt to 4,000 cSt,preferably 20 cSt to 2,000 cSt, and most preferably 4 cSt to 250 cSt.The PAO may have a viscosity index of 70 to 350, preferably 80 to 300,preferably above 100, preferably above 150, preferably above 170,preferably above 200, and most preferably 120 to 300. The PAO may have apour point as measured by ASTM D97 method or equivalent method of lessthan 0° C., or preferably less than −15° C., or less than −25° C., orless than −35° C., or less than −40° C. Usually, it is preferred to usePAO that has low pour point and high VI as starting material for thesynthesis of dispersant to ensure a final product with optimumviscometric properties.

The PAO is preferably prepared by oligomerization or polymerization inthe presence of an activated metallocene catalyst. Manufacture of PAO inthe presence of metallocene catalysts is disclosed, for example, in WO2007/011462 A1, WO 2007/011459 A1, and WO 2007/011973 A1, all of whichare incorporated herein by reference.

The PAO can be prepared from any one or two or more alpha-olefinscontaining 3 to 24 carbons. When a single alpha-olefin is used as afeed, it is preferred to select a feed olefin from C₃ to C₁₈ linearalpha-olefin (LAO), or preferably from C₄ to C₁₆-LAO, or preferably fromC₆ to C₁₄-LAO, or preferably from C₆ to C₁₂-LAO, or preferably from C₆to C₁₀-LAO, or preferably C₈ to C₁₂-LAO, or preferably C₆ or C₈ or C₁₀LAO. When a mixture of alpha-olefins containing two or more linearalpha-olefins is used as the feed, the mixed alpha-olefins can beselected from any C₃ to C₂₄-LAO, or preferably C₄ to C₂₀-LAO, orpreferably C₆ to C₂₀-LAO, or preferably C₆ to C₁₈-LAO, or preferably C₄to C₁₈-LAO, or preferably C₆ to C₁₄-LAO, or preferably C₆ to C₁₂-LAO, ormost preferably C₈ to C₁₂-LAO. When a mixture of alpha-olefinscontaining two or more linear alpha-olefins is used as the feed, thepreferred composition of the feed LAOs should have an average carbonlength of greater than 4. For example, a feed containing 50 wt %1-butene and 50 wt % I-pentene has an average carbon length of 4.4. Afeed containing 50 wt % 1-butene and 50 wt % 1-hexene has an averagecarbon length of 4.8. A feed containing 50 wt % 1-butene and 50 wt %1-octene has an average carbon length of 5.3. A feed containing 50 wt %1-butene and 50 wt % 1-decene has an average carbon length of 5.7. Afeed containing 50 wt % 1-butene and 50 wt % 1-dodecene has an averagecarbon length of 6. A feed containing 50 wt % 1-butene and 50 wt %1-tetradecene has an average carbon length of 6.2. A feed containing 50wt % 1-hexene and 50 wt % 1-octene has an average carbon length of 6.9.A feed containing 33.3 wt % 1-hexene and 66.7 wt % 1-dodecene has anaverage carbon length of 9.0. A feed containing 33.3 wt % 1-hexene, 33.3wt % 1-octene, and 33.3 wt % 1-dodecene has an average carbon length of8. Other combinations of mixed linear alpha-olefins, such as C₆/C₁₄,C₆/C₈/C₁₀/C₁₂, C₆/C ₁₀/C₁₄, C₈/C₁₀/C₁₂, C₈/C₁₄, and the like can also beused. The choice of linear alpha-olefins typically depends onavailability. Usually, it is most preferred to choose the linearalpha-olefins mixture such that the average carbon number of the mixtureis greater than 4, or alternatively greater than 4.5, alternativelygreater than 5, alternatively greater than 5.5, alternatively greaterthan 6, and most alternatively greater than 6.5. In all cases, it isalso preferred to have the average carbon length no larger than 14,preferably no larger than 12, preferably no larger than 11, preferablyno larger than 10.5, and most preferably no larger than 10. Usually, thelarger the average carbon length of the feed olefins, the higher VI forthe liquid PAO product. Higher VI is usually more beneficial. However,when the average carbon number of the feed olefins is much above 11 or12, the long chain hydrocarbon portion of the PAO may cause severe lowtemperature viscosity increase due to partial gel formation or partialcrystallization, which is undesirable. Therefore, a preferred averagecarbon length for the feed olefins is between 4.5 and 11.5 and mostpreferably 4.5 to 10.5.

In a preferred process, feed olefins, usually linear-alpha-olefins, arepolymerized in the presence of activated metallocene catalysts, whichresults in a PAO containing only un-isomerized branches. More preferredPAO usually contains branches of two or more carbons. Examples of thebranches are ethyl, propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl,n-octyl, n-nonyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, ormixture of any of them. More preferred branches are ethyl, n-butyl,n-hexyl, n-octyl, n-decyl, n-tetradecyl, or mixture of them. Dispersantsderived from these PAO with linear branches are more desirable than thedispersants prepared from polyolefins prepared from branched olefins,such as iso-butylene.

The PAO is reacted with maleic anhydride (MA) to form thepolyalphaolefin succinic anhydride (PAO-SA) and subsequently theanhydride is reacted with one or more of polyamines, aminoalcohols, andalcohols/polyols to form polyalphaolefin succinimide, polyalphaolefinsuccinamide, polyalphaolefin succinic acid ester, polyalphaolefinoxazoline, polyalphaolefin imidazoline,polyalphaolefin-succinamide-imidazoline, and mixtures thereof asrepresented by the following reaction sequences:

PAO (unhydrogenated)+maleic anhydride→PAO-SA (succinic anhydride)

PAO-SA+polyamine→PAO-imide and PAO-amide and PAO-amide-imidazoline

PAO-SA+alcohol/polyol→PAO-acid ester

PAO-SA+amino alcohol→PAO-amide-oxazoline

Some reaction products are depicted below:

wherein R₁ is a branched C₂₀-C₂₀₀ alkyl or alkenyl group derived frompoly alpha-olefins; R₂ and R₃ are independently a C₁-C₁₀ branched orstraight chained alkylene group; n is an integer from 1 to 10; R₅ and R₆are H or R₅ and R₆ together along with the N atom bound thereto form thegroup:

wherein R₇ is a branched or straight-chained C₂₀-C₂₀₀ alkyl or alkenylgroup derived from polyalphaolefins; wherein the N atom bound to the R₂and R₃ groups above is optionally substituted in one or more places withthe following group:

—R₈—R₉

wherein R₈ is a C₁-C₁₀ branched or straight chained alkylene group; andR₉ is NH₂ or

wherein R₁₀ is a branched or straight-chained C₂₀-C₂₀₀ alkyl or alkenylgroup; and wherein the R₂—NH—R₃ group is optionally interrupted in oneor more places by a heterocyclic or homocyclic cycloalkyl group, andwherein one or more of R₁, R₇ and R₁₀ groups is a substituted orunsubstituted poly-alpha-olefin. For example, one or more of R₁, R₇ andR₁₀ can be independently selected from poly(1-pentene) (POP),poly(1-decene) (POD), or other poly-alpha-olefins in which each repeatunit contains 5-18 carbon atoms, i.e., poly(1-pentene), poly(1-hexene),poly(1-heptene), poly(1-octene), poly(1-nonene), poly(1-undecene),poly(1-dodecene), or poly-alpha-olefins prepared from mixture of C₃ toC₂₄ linear-alpha-olefins. The poly-alpha-olefins can have from 20 to 200carbon atoms in the polymer.

Based on the bonding environment, the nitrogen atom in theabove-mentioned mixtures or combinations of compounds can have any ofseveral different types of bonding. The types of bonding are illustratedin the following structures:

Primary amine (two hydrogen atoms bonded with nitrogen atom)

Secondary amine (one hydrogen atom bonded with nitrogen atom). R_(a) andR_(b) can be the same or different.

Tertiary amine (no hydrogen atom bonded with nitrogen atom. R_(a), R_(b)and R_(c) can be the same or can be complete different.

Imide (nitrogen atom bonded in the succinyl anhydride ring, ring isclosed). R_(a) and R_(b) can be the same or can be different.

Secondary Amide (nitrogen atom bonded with a carbonyl group and have onehydrogen atom bonded to nitrogen atom). R_(a) and R_(b) can be the sameor can be different.

Tertiary Amide (nitrogen atom bonded with a carbonyl group and have nohydrogen atom bonded to nitrogen atom. R_(a), R_(b) and R_(c) can be thesame or different.

In some embodiments, at least one of R₁, R₇ and R₁₀, as defined above,is poly-1-decene (POD). In one embodiment, the additive is selected from

It will be understood by persons of ordinary skill in the art thatvarious chemical structures as shown above shall have very differentratios of their functional groups (i.e. amine(primary-secondary/tertiary)/amide/imide). For example, the amine toimide ratio in structure (I) is 3:2 while the ratio in structure (II) is4:1. To be more specific, although the amine to imide ratio is the samein structure (III) as in structure (II), the tertiary amine to primaryamine ratio is 1:1 in structure (III) but at 0:4 in structure (II). Therelative amine/amide/imide ratios can be important as their performancelevels could be very different.

The PAO-MA maleination reaction is carried out at a temperature of 120to 280° C., preferably 150° C. to 250° C., and most preferably 170° C.to 220° C. The reaction can be carried out at a pressure of 2 psi to 100psi, preferably sub-atmospheric pressure to 50 psi, and most preferablyatmospheric pressure to 30 psi. The reaction is carried out (reactiontime) for 1 hour to 48 hours, preferably 2 hours to 24 hours, and mostpreferably 4 hours to 12 hours. Analogous procedures for maleination ofpolyisobutylene (PIB) are disclosed, for example, in U.S. Pat. Nos.6,051,537, 6,355,074, 6,355,603, 3,284,410 and 3,948,800. Excess molarquantity of maleic anhydride can be used to increase conversion rates.However, since unhydrogenated PAO has higher reactivity than typicalpolyisobutylene, a lower reaction temperature can be employed. Forexample, most PIB-maleic anhydride reaction temperature is 190° C. ormore, while in the case of PAO-maleic anhydride, reasonable conversioncan be achieved at 140° C. or more.

The synthesis of PAO-succinic anhydride can be carried out through athermal process (without catalyst) at relatively high temperature or achlorine catalyzed process at much lower reaction temperature. A typicalset of process conditions can be described by the batch reactorconditions as follows. A CSTR reactor equipped with cooling tower,mechanical agitator, gas inlet and outlet can be employed. The systemwas flushed with nitrogen to avoid oxidation and the mixture (PAO andmaleic anhydride) was heated to 110° C., then to 140° C. with vigorousstirring for an adequate amount of reaction time. The unreacted maleicanhydride was stripped by heating under nitrogen stream at 190° C. Theresidue is the desired polyalphaolefin-substituted succinic anhydridehaving an appropriate saponification equivalent number as determined byASTM procedure D94. If chlorine process is chosen, excess amount ofgaseous chlorine is added beneath the surface to achieve the bestcatalytic effect and the reaction temperature can be as low as 130° C.to 140° C. range. The subsequent reaction from polyalphaolefin succinicanhydride to polyalphaolefin succinimide and/or succinamide can becarried out with a commercial mixture of alkylene polyamines having from3 to 10 nitrogen atoms per molecule and the presence of some mineral oilto reduce viscosity. The reaction mixture is heated to 135° C. to 155°C. and stripped by blowing with nitrogen. The reaction mixture isfiltered to yield the filtrate as an oil solution of the desiredproduct. Polyalphaolefin amide imidazoline can be prepared by reacting apolyalphaolefin succinamide with a stoichiometric excess of a polyamineand extra reaction time.

It is advantageous to use the PAO described above for the synthesis ofthe dispersant. These PAOs usually have higher reactivity because theolefin composition is rich in vinylidene or 1,2-disubstituted olefinsand low in tri- or tetra-substituted olefins. Vinylidene and1,2-disubstituted olefins have higher reactivity with maleic anhydride.Typically, the total amount of vinylidene and 1,2-di-substituted olefincontent is great than 50% of the total olefins, preferably greater than60%, preferably greater than 70%, preferably greater than 80%,preferably greater than 90%. The most preferred range is from 60 to 85%.The PAOs produced in this method has less impurities than many of thetraditional polymeric olefins such as poly-isobutylene (PIB). Some ofthe impurities, such as fluorides or aluminum, may act as inhibitor forthe reaction with maleic anhydride. The PAOs produced in this methodhave much better thermal stability than PIB. Thus, it will not decomposeunder high reaction temperatures usually required for maleic anhydridereaction. As a result, the adduct has more uniform molecular size, whichprovides better dispersancy. In contrast, PIB decomposes at hightemperature, resulting in reduced product yields and lower productquality.

The dispersants are admixed with lubricant base stocks to form thelubricant blends of the present disclosure. Any known base stock may beemployed, including those of Group I, Group II, Group+, Group III, GroupIII+, Group IV, and Group V. Gas-to-liquid (GTL) base stocks, which aresometimes classified as Group III+ base stocks, are also useful.Combinations of the foregoing base stocks may also be employed. Thesebase stocks may be obtained from either synthetic or natural/renewablesources.

The lubricating oil base oil can be any oil boiling in the lube oilboiling range, typically between 100° C. to 450° C. In the presentspecification and claims the terms base oil(s) and base stock(s) areused interchangeably.

A wide range of lubricating base oils is known in the art. Lubricatingbase oils include natural oils and synthetic oils. Natural and syntheticoils (or mixtures thereof) can be used as unrefined, refined, orrerefined (the latter is also known as reclaimed or reprocessed oil).Unrefined oils are those obtained directly from a natural or syntheticsource and used without added purification. These include shale oilobtained directly from retorting operations, petroleum oil obtaineddirectly from primary distillation, and ester oil obtained directly froman esterification process. Refined oils are similar to the oilsdiscussed for unrefined oils except refined oils are subjected to one ormore purification steps to improve at least one lubricating oilproperty. Purification processes known in the art include solventextraction, secondary distillation, acid extraction, base extraction,filtration, and percolation. Rerefined oils are obtained by processesanalogous to refined oils but using an oil that has been previously usedas feed stock.

Groups I, II, III, IV and V are broad categories of base oil stocksdeveloped and defined by the American Petroleum Institute (APIPublication 1509; www.API.org) to create guidelines for lubricant baseoils. Group I base stocks generally have a viscosity index of 80 to 120and contain greater than 0.03% sulfur and less than 90% saturates. GroupII base stocks generally have a viscosity index of 80 to 120, andcontain less than or equal to 0.03% sulfur and greater than or equal to90% saturates. Group III stocks generally have a viscosity index greaterthan 120 and contain less than or equal to 0.03% sulfur and greater than90% saturates. Group IV includes polyalphaolefins (PAO). Group V basestock includes base stocks not included in Groups I-IV. The table belowsummarizes properties of each of these five groups.

Base Oil Properties Saturates Sulfur Viscosity Index Group I <90and/or >0.03% and ≧80 and <120 Group II ≧90 and ≦0.03% and ≧80 and <120Group III ≧90 and ≦0.03% and ≧120 Group IV Includes polyalphaolefins(PAO) and GTL products Group V All other base oil stocks not included inGroups I, II, III or IV

Useful lubricant base stocks preferably exhibit a pour point of lessthan 10° C., more preferably less than 0° C., and most preferably lessthan −10° C. according to ASTM D 97. The lubricant base stockspreferably exhibit a kinematic viscosity at 40° C. from 4 to 80,000centi-Stokes (cSt) and more preferably from 5 cSt to 50,000 cSt at 40°C. according to ASTM D445. The lubricant base stocks preferably exhibita kinematic viscosity at 100° C. of 1.5 to 5,000 cSt, more preferably 2cSt to 3,000 cSt, and most preferably 3 cSt to 500 cSt. Low viscositylubricant base stocks are particularly useful in automotive motor oilapplications, namely those with kinematic viscosities at 100° C. from 3cSt to 15 cSt and more typically 3 cSt to 8 cSt. Low viscosity lubricantbase stocks are particularly useful for 0W20 and 0W30 motor oils.

Lubricant blends of the present disclosure may optionally include otherconventional lubricant additives, such as detergents, antioxidants,anti-wear additives, pour point depressants, viscosity index modifiers,friction modifiers, defoaming agents, corrosion inhibitors, wettingagents, rust inhibitors, seal swell agents and the like. The additivesmay be incorporated to make a finished lubricant product that hasdesired viscosity and physical properties. Typical additives used inlubricant formulation can be found in the book “Lubricant Additives,Chemistry and Applications”, Ed. L. R. Rudnick, Marcel Dekker, Inc. 270Madison Ave. New York, N.J. 10016, 2003.

Lubricant blends of the present disclosure are useful as oils or greasesfor any device or apparatus requiring lubrication of moving and/orinteracting mechanical parts, components, or surfaces. Usefulapparatuses include engines and machines. The lubricant blends are mostsuitable for use in the formulation of automotive crank-case lubricants,automotive gear oils, transmission oils, many industrial lubricantsincluding circulation lubricant, industrial gear lubricants, grease,compressor oil, pump oils, refrigeration lubricants, hydrauliclubricants, metal working fluids. Lubricant blends of the presentdisclosure are particularly useful in automotive applications ascrank-case oil, i.e., motor oil.

Preferred lubricant blends with PAO-based dispersants preferably exhibitlower viscosities than PIB-based dispersants at equal amounts and atcomparable molecular weights and more preferably do so across atemperature range of −40° C. to 100° C. Comparative viscosities can bemeasured by ASTM method D665-3 for Kv 40, by D665-5 for Kv 100, and ASTMD5293 for Cold Crank Simulation (CCS).

The following are examples of the present disclosure and are not to beconstrued as limiting.

EXAMPLES

Lubricant blends containing PAO-based succinimide (PAO-imide) of thepresent disclosure were prepared and compared for viscosity propertieswith respect to conventional blends containing PIB-based succinimide(PIB-imide).

A poly-alpha-olefin (PAO) with M_(n) of 1160 was synthesized accordingto substantially the same procedures set forth in Example 10 of WO2007011973, herein incorporated by reference, at 90° C. and with H₂ feedrate of 5 scc/minute. The polymer fraction was isolated from the crudeproduct by distillation at 180° C./0.1 millitorr vacuum to remove anylight boiling fraction. This PAO exhibited the same degree ofunsaturation as measured by bromine number as a 900 molecular weight PIBused for the synthesis of commercial dispersant. The PIB has brominenumber of 16.6 and the PAO has bromine number of 16.

A PAO-imide dispersant, Example 1, was synthesized according to thefollowing procedures and compared with the analogous PIB-imidedispersant, Example 2, of equal molecular weight (Table 1). Theresulting succinimide dispersants had very similar overall N (nitrogen)levels (3.9 and 4.1 wt % N for PIB-imide and PAO-imide). It issurprising to note that although the starting PIB and PAO have the samemolecular weight and same bromine number, the PAO-imide has much lowerKv 100° C. and Kv 40° C. than PIB-imide. Generally, it is preferred tohave an oil-diluted dispersant of Kv 100° C. much less than 200 cS andKv 40° C. of much less than 10,000 cS. A lower viscosity dispersantallows broader formulation space for low viscosity, fuel efficientengine lubricants.

The dispersants of Example 1 and 2 were blended with a 4 cS Gr III+ basestock at 10 wt % based on the total weight of the blend. The PAO-imideblend of Example 3 had a lower Kv at 40° C. and 100° C. than thePIB-imide blend of Example 4. The lower viscosity is particularlybeneficial for formulating into 0W20 and 0W30 lubricants and motor oils.

The calculated viscosities at −15° C., −30° C. and −40° C. for thePAO-imide blend of Example 3 also are significantly lower than for thePIB-imide blend of Example 4. The viscosities were calculated accordingto the extrapolation of VI calculation by ASTM D2270 method. The lowerviscosity for the blends is particularly beneficial for formulation oflow-vis grade-finished lubricants.

TABLE 1 Example No. 1 2* Dispersant Type PAO-imide PIB-imide Kv100° C.,cS 36.50 224.50 Kv 40° C., cS 425.60 10,046.40 VI (viscosity index) 12099 Example No. 3 4 Blend Properties Wt % SI in Blend 10 10 BlendProperties Kv100° C., cS 4.55 4.95 Kv 40° C., cS 19.32 21.91 VI 158 159Calculated Low Temperature Kv at −15° C., cS 314.2 387.9 Kv at −30° C.,cS 1141.5 1464 Kv at −40° C., cS 3338.0 4413 % Less Kv Increase comparedto Example 4 100° C. Kv reduction 7.8 Control 40° C. Kv reduction 13.4Control −15° C. Kv reduction 23.5 Control −30° C. Kv reduction 28.3Control −40° C. Kv reduction 32.2 Control *not an example of the presentdisclosure

The two dispersants used in the blends of Example 5 and 6 weresynthesized in the same manner as the dispersants used in Example 1 and2 except no diluent oil was added to the final step for the succinimidesynthesis. The PAO-imide blend of Example 5 and the PIB-imide blend ofExample 6 were prepared with a 4 cS Gr III+ base stock. The propertiesof the blends of Example 7 and 8, and the dispersants PAO-imide andPIB-imide are summarized in Table 2. Similar reduction of viscosity wasobserved with the PAO-imide blend (Example 5). This example furtherdemonstrated the advantages of PAO-imide dispersants in that the blendexhibited very low viscosity and good VI compared to the blend havingPTB-imide. Because of low viscosity, the PAO-imide is easy to handleduring synthesis and no diluent oil was needed at the end of thesynthesis to cut down oil viscosity. It is desirable to avoid use ofdiluent oil as it allows for better control of base stock purity in thefinal formulation. Generally, it is preferred to have pure dispersant ofKv 100° C. less than 700 cS and a Kv 40° C. of less than 60,000 cS. Alower viscosity dispersant without diluent oil affords broaderformulation tolerance in low viscosity, fuel efficient, enginelubricants.

TABLE 2 Example No. 5 6* Dispersant Type PAO-imide PIB-imide Kv 100° C.,cS 96.77 788.67 Kv 40° C., cS 1,344.00 60,985.31 VI 156 134 Example No.7 8 Wt % SI in Blend 10 10 Blend Properties Kv 100° C., cS 4.65 5.08 Kv40° C., cS 19.90 23.15 VI 159 155 Calculated Low Temperature Kv at −15°C., cS 328.1 441.1 Kv at −30° C., cS 1198.1 1729.8 Kv at −40° C., cS3516.6 5392.5 % Kv Reduction Compared to PIB-imide blend %100° C. Kvreduction 8.2 control % 40° C. Kv reduction 16.3 control % −15° C. Kvreduction 34.4 control % −30° C. Kv reduction 44.4 control % −40° C. Kvreduction 53.3 control *not an example of the present disclosure

Synthesis Procedures: Synthesis of PAO-imide (poly-alpha-olefinsuccinimide, Example 1)

A PAO (as described above, 75 g) was added to a round-bottom flaskequipped with N₂ inlet, stirrer, and condenser together with crushedmaleic anhydride (15 g, 2 eq). The system was flushed with nitrogen andthe mixture heated to 142° C. with vigorous stirring for 6 hours. Theunreacted maleic anhydride was stripped by heating under nitrogen streamat 200° C. The saponification number of the product, PAO-succinicanhydride (PAO-SA), was 79.6.

A four-necked flask equipped with Dean Stark trap, condenser,thermometer, stirrer and nitrogen inlet was charged with mPAO-SA (50 g,1 eq), a commercial mixture of ethylene polyamines (tetraethylepentamineor TEPA**, 9.4 g, 1 eq) and diluent oil (100 sec Solvent dewaxed,paraffinic neutral, 25 g). The mixture was heated to 138° C. and stirredfor 4 hours. The warm product was filtered. IR analysis confirmedcomplete reaction. Yield: 80.0 g of a clear, brown fluid.

Synthesis of PIB-imide (polyisobutylene succinimide, Example 2)

PIB (Aldrich product no 388696, 125 g) was added to a round-bottom flaskequipped with N₂ inlet, stirrer, and condenser, together with crushedmaleic anhydride (26.6 g, 2 eq based on 900 M_(n) of PIB). The systemwas flushed with nitrogen and the mixture heated to 110° C. withvigorous stirring for 30 minutes. The reaction mixture was heated at207° C-234° C. and stirred for 5.5 hours. Remaining maleic anhydride wasstripped by heating under nitrogen stream at 200° C. The saponificationnumber of the product, PIB-succinic anhydride (PIB-SA) was 80.3.

A four-necked flask equipped with Dean-Stark trap, condenser,thermometer, stirrer and nitrogen inlet was charged with mPIB-SA (94 g,1 eq), a commercial mixture of ethlene polyamines(tetraethylenepentamine or TEPA**, 17.7 g, 1 eq) and diluent oil (100sec Solvent dewaxed, paraffinic neutral, 50 g). The mixture was heatedto 138° C. and begin stirred for 4 hours. The warm product was filtered.IR analysis confirmed complete reaction. Yield: 148.0 clear, viscous,brown fluid. *The saponification test method was similar to ASTM D94method. It was used to measure the amount of anhydride functionality inthe succinic anhydride product.**TEPA is mixture of mostlytriethylenetetraamines, tetraethylenepentamine, pentaethylenehexamineand was obtained from The Dow Chemical Company.

1. A lubricant blend comprising one or more lubricant base stocks and adispersant chosen from: a polyalphaolefin succinimide, a polyalphaolefinsuccinamide, a polyalphaolefin acid ester, a polyalphaolefin oxazoline,a polyalphaolefin imidazoline, a polyalphaolefin succinamideimidazoline, and combinations thereof, wherein the one or moredispersants are present at 2 to 20 wt % based on the total weight of theblend, and wherein the one or more dispersants and the one or morelubricant base stocks are together present at 85 wt % or more of thetotal weight of the blend.
 2. The blend of claim 1, wherein the one ormore dispersants and the one or more lubricant base stocks are togetherpresent at 90 wt % or more of the total weight of the blend.
 3. Theblend of claim 1, wherein the one or more dispersants and the one ormore lubricant base stocks are together present at 95 wt % or more ofthe total weight of the blend.
 4. The blend of claim 1, wherein the oneor more dispersants are present at 5 to 15 wt % based on the totalweight of the blend.
 5. The blend of claim 1, wherein the one or moredispersants are present at 5 to 10 wt % based on the total weight of theblend.
 6. The blend of claim 1, wherein the one or more lubricant basestocks is chosen from a Group I, Group II, Group II+, Group III, GroupIII+, Group IV, Group V, and combinations thereof.
 7. The blend of claim1, wherein the one or more lubricant base stocks includes a Group III+base stock.
 8. The blend of claim 1, wherein the dispersant exhibits akinematic viscosity at 100° C. of less than 700 cS, a kinematicviscosity at 40° C. of less than 50,000 cS, and a viscosity index ofgreater than
 135. 9. The blend of claim 1, wherein the dispersantdiluted with up to 35 wt % mineral oil exhibits a kinematic viscosity at100° C. of less than 200 cS, a kinematic viscosity at 40° C. of lessthan 10,000 cS, and a viscosity index of greater than 100, from 100 to200.
 10. The blend of claim 1, wherein the dispersant is apolyalphaolefin succinimide.
 11. The blend of claim 1, wherein thedispersant is a polyalphaolefin succinamide.
 12. The blend of claim 1,wherein the dispersant is a polyalphaolefin acid ester.
 13. The blend ofclaim 1, wherein the dispersant is a polyalphaolefin oxazoline.
 14. Theblend of claim 1, wherein the dispersant is a polyalphaolefinimidazoline.
 15. The blend of claim 1, wherein the dispersant is apolyalphaolefin succinamide.
 16. A process for making a lubricant blendcomprising: admixing an amount of one or more lubricant base stocks andan amount of a dispersant chosen from: a polyalphaolefin succinimide, apolyalphaolefin succinamide, a polyalphaolefin acid ester, apolyalphaolefin oxazoline, a polyalphaolefin imidazoline, apolyalphaolefin succinamide imidazoline, and combinations thereof,wherein the one or more dispersants are present at 2 to 20 wt % based onthe total weight of the blend, and wherein the one or more dispersantsand the one or more lubricant base stocks are together present at 85 wt% or more of the total weight of the blend.
 17. The process of claim 16,wherein the one or more lubricant base stocks is chosen from a Group I,Group II, Group II+, Group III, Group III+, Group IV, Group V, andcombinations thereof.
 18. The process of claim 16, wherein thedispersant exhibits a kinematic viscosity at 100° C. of less than 700cS, a kinematic viscosity at 40° C. of less than 50,000 cS, and aviscosity index of greater than
 135. 19. The process of claim 16,wherein the dispersant diluted with up to 35 wt % mineral oil exhibits akinematic viscosity at 100° C. of less than 200 cS, a kinematicviscosity at 40° C. of less than 10,000 cS, and a viscosity index ofgreater than 100, from 100 to
 200. 20. A method for lengthening theservice life of a lubricant formulation comprising: admixing with one ormore lubricant base stocks an amount of a dispersant chosen from: apolyalphaolefin succinimide, a polyalphaolefin succinamide, apolyalphaolefin acid ester, a polyalphaolefin oxazoline, apolyalphaolefin imidazoline, a polyalphaolefin succinamide imidazoline,and combinations thereof, and utilizing the lubricant formulation as anoil or grease in a device or apparatus requiring lubrication of movingand/or interacting mechanical parts, components, or surfaces, whereinthe one or more dispersants are present at 2 to 20 wt % based on thetotal weight of the blend, and wherein the one or more dispersants andthe one or more lubricant base stocks are together present at 85 wt % ormore of the total weight of the blend.
 21. The method of claim 20,wherein the one or more lubricant base stocks is chosen from a Group I,Group II, Group II+, Group III, Group III+, Group IV, Group V, andcombinations thereof.
 22. The method of claim 20, wherein the dispersantexhibits a kinematic viscosity at 100° C. of less than 700 cS, akinematic viscosity at 40° C. of less than 50,000 cS, and a viscosityindex of greater than
 135. 23. The method of claim 20, wherein thedispersant diluted with up to 35 wt % mineral oil exhibits a kinematicviscosity at 100° C. of less than 200 cS, a kinematic viscosity at 40°C. of less than 10,000 cS, and a viscosity index of greater than 100,from 100 to
 200. 24. A lubricant formulation prepared by the processcomprising: admixing with one or more lubricant base stocks an amount ofa dispersant chosen from: a polyalphaolefin succinimide prepared byreacting an unhydrogenated polyalphaolefin with maleic anhydride to forma polyalphaolefin anhydride followed by reacting the polyalphaolefinanhydride with a polyamine, a polyalphaolefin succinamide prepared byreacting an unhydrogenated polyalphaolefin with maleic anhydride to forma polyalphaolefin anhydride followed by reacting the polyalphaolefinanhydride with a polyamine, a polyalphaolefin acid ester prepared byreacting an unhydrogenated polyalphaolefin with maleic anhydride to forma polyalphaolefin anhydride followed by reacting the polyalphaolefinanhydride with a polyamine, a polyalphaolefin oxazoline prepared byreacting an unhydrogenated polyalphaolefin with maleic anhydride to forma polyalphaolefin anhydride followed by reacting the polyalphaolefinanhydride with an aminoalcohol, a polyalphaolefin amide-imidazolineprepared by reacting a polyalphaolefin succinamide with a polyamine, andcombinations of two or more of the foregoing, wherein the one or moredispersants are present at 2 to 20 wt % based on the total weight of theblend, and wherein the one or more dispersants and the one or morelubricant base stocks are together present at 85 wt % or more of thetotal weight of the blend.